PhoenixFire

2 years ago

How do you calculate the momentum of two objects immediately after a perfectly elastic collision?
Do you need to find the velocities of the two objects after collision and then use the formula of p=mv. where p is momentum vector, m is mass of the object, and v is the velocity vector?
Or is there another way to find the linear momentum?

So what I got from those two links was basically that I do need to calculate the final velocities.
\[v_{1f}={(m_1 - m_2)v_{1i} + 2m_2 v_{2i} \over m_1+m_2}\]\[v_{2f}={(m_2-m_1)v_{2i}+2m_1v_{1i} \over m_1+m_2}\]
Then apply the momentum formula\[\mathbf {\vec p}=m {\mathbf{\vec v}}\]
Kinda strange since the next question asks me to find the velocities.. You'd think they would put it in the right order to help you learn the method.

The problem you posted it's a 2-dimensional collision and momentum is still conserved but you have to account for the momentum in 2 dimensions.
That's a bit tougher and I admit that I haven't done one of those in a while :)